The present invention relates to a breather cap for a liquid petroleum tank and is intended to insure that the air passing into the petroleum tank is both clean and dry.
The problems associated with the contamination of petroleum fluids are well known. As the enclosed oil in an industrial machine cools when the operation of the machine ceases, a partial vacuum is typically created in the oil reservoir. This partial vacuum draws air into the oil reservoir. Unfortunately, the air drawn into the reservoir is often contaminated with dust and with moisture. As a result, the oil within the tank is contaminated and must be periodically changed to avoid damage to the machine it lubricates.
Not only is the oil directly contaminated by the dust and moisture in the air, the presence of moisture within the oil reservoir often causes oxidation of the oil reservoir itself and the oxidation products serve as a further contaminant to the oil.
The filtering of the air entering an oil reservoir to remove dust particles is well known and is shown for example in the Risse et al U.S. Pat. No. 3,160,487 dated Dec. 8, 1964, the Fisher U.S. Pat. No. 3,244,314 dated Apr. 5, 1966 and the Claar U.S. Pat. No. 3,546,853 dated Dec. 15, 1979. In filters of this type, air is generally permitted to pass upwardly through apertures in the bottom of the filter, through a filter material, and then downwardly into the oil reservoir. However, such systems do not provide for the removal of moisture from the air.
Attempts have been made to dry the air entering an oil reservoir. In systems such as illustrated in the McCall U.S. Pat. No. 2,603,308 dated July 15, 1952, air is permitted to pass upwardly through a filter element into a cavity containing a desiccant. Such systems generally do not provide for the viewing of the desiccant without removal of the filter cap and the periodic removal of the filter cap to check the condition of the desiccant results in increased contamination. Failure to check the desiccant at periodic intervals increases the likelihood that the desiccant will be contaminated and thus not effective.
A further problem with systems such as illustrated in the McCall patent is that the air passing into the dust filter may pass through the dust filter into the oil reservoir without passing through the desiccant. In this way, the value of the desiccant to the system may be materially reduced.
It is accordingly an object of the present invention to obviate these and other deficiencies of such known systems and to provide a novel hygroscopic breather cap for a petroleum tank such as an oil reservoir.
Another object of the present invention is to provide a novel hygroscopic breather cap in which dust is removed from the air prior to passage through the desiccant.
Yet another object of the present invention is to provide a novel hygroscopic breather cap for a liquid petroleum tank which the air entering the tank is forced to pass through a substantial volume of desiccant.
A further object of the present invention is to provide a novel hygroscopic breather cap which prevents the passage of desiccant fines into the petroleum tank.
Still a further object of the present invention is to provide a novel construction for a hygroscopic breather cap in which the condition of the desiccant may be readily observed without exposing the contents of the petroleum tank or the desiccant to the atmosphere.
Still a further object of the present invention is to provide a novel construction for a hygroscopic breather cap in which the effective air input openings may be easily increased in the field to adapt the breather cap for a particular application.
These and many other objects and advantages of the present invention will be readily apparent from the claims and from the following detailed description when read in conjunction with the appended drawings.